diff --git a/core/modules/simpletest/src/InstallerTestBase.php b/core/modules/simpletest/src/InstallerTestBase.php
index 369c3ab..d51b2e9 100644
--- a/core/modules/simpletest/src/InstallerTestBase.php
+++ b/core/modules/simpletest/src/InstallerTestBase.php
@@ -8,6 +8,7 @@
 use Drupal\Core\Language\Language;
 use Drupal\Core\Session\UserSession;
 use Drupal\Core\Site\Settings;
+use Drupal\Tests\RequirementsPageTrait;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpFoundation\Request;
@@ -22,6 +23,8 @@
  */
 abstract class InstallerTestBase extends WebTestBase {
 
+  use RequirementsPageTrait;
+
   /**
    * Custom settings.php values to write for a test run.
    *
@@ -213,12 +216,7 @@ protected function setUpSettings() {
    * @see system_requirements()
    */
   protected function setUpRequirementsProblem() {
-    // By default, skip the "recommended PHP version" warning on older test
-    // environments. This allows the installer to be tested consistently on
-    // both recommended PHP versions and older (but still supported) versions.
-    if (version_compare(phpversion(), '7.0') < 0) {
-      $this->continueOnExpectedWarnings(['PHP']);
-    }
+    // Do nothing.
   }
 
   /**
@@ -255,32 +253,8 @@ protected function refreshVariables() {
    *   a warning not in the list is present, a fail is raised.
    */
   protected function continueOnExpectedWarnings($expected_warnings = []) {
-    // Don't try to continue if there are errors.
-    if (strpos($this->getTextContent(), 'Errors found') !== FALSE) {
-      return;
-    }
-    // Allow only details elements that are directly after the warning header
-    // or each other. There is no guaranteed wrapper we can rely on across
-    // distributions. When there are multiple warnings, the selectors will be:
-    // - h3#warning+details summary
-    // - h3#warning+details+details summary
-    // - etc.
-    // We add one more selector than expected warnings to confirm that there
-    // isn't any other warning before clicking the link.
-    // @todo Make this more reliable in
-    //   https://www.drupal.org/project/drupal/issues/2927345.
-    $selectors = [];
-    for ($i = 0; $i <= count($expected_warnings); $i++) {
-      $selectors[] = 'h3#warning' . implode('', array_fill(0, $i + 1, '+details')) . ' summary';
-    }
-    $warning_elements = $this->cssSelect(implode(', ', $selectors));
-
-    // Confirm that there are only the expected warnings.
-    $warnings = [];
-    foreach ($warning_elements as $warning) {
-      $warnings[] = trim((string) $warning);
-    }
-    $this->assertEqual($expected_warnings, $warnings);
+    $this->assertFalse(strpos($this->getTextContent(), 'Errors found'));
+    $this->assertWarningSummaries($expected_warnings);
     $this->clickLink('continue anyway');
   }
 
diff --git a/core/tests/Drupal/FunctionalTests/Installer/InstallerTestBase.php b/core/tests/Drupal/FunctionalTests/Installer/InstallerTestBase.php
index 5ea1e58..6e48b4c 100644
--- a/core/tests/Drupal/FunctionalTests/Installer/InstallerTestBase.php
+++ b/core/tests/Drupal/FunctionalTests/Installer/InstallerTestBase.php
@@ -8,6 +8,7 @@
 use Drupal\Core\Site\Settings;
 use Drupal\Core\Test\HttpClientMiddleware\TestHttpClientMiddleware;
 use Drupal\Tests\BrowserTestBase;
+use Drupal\Tests\RequirementsPageTrait;
 use GuzzleHttp\HandlerStack;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;
@@ -19,6 +20,8 @@
  */
 abstract class InstallerTestBase extends BrowserTestBase {
 
+  use RequirementsPageTrait;
+
   /**
    * Custom settings.php values to write for a test run.
    *
@@ -281,32 +284,8 @@ protected function refreshVariables() {
    *   a warning not in the list is present, a fail is raised.
    */
   protected function continueOnExpectedWarnings($expected_warnings = []) {
-    // Don't try to continue if there are errors.
-    if (strpos($this->getTextContent(), 'Errors found') !== FALSE) {
-      return;
-    }
-    // Allow only details elements that are directly after the warning header
-    // or each other. There is no guaranteed wrapper we can rely on across
-    // distributions. When there are multiple warnings, the selectors will be:
-    // - h3#warning+details summary
-    // - h3#warning+details+details summary
-    // - etc.
-    // We add one more selector than expected warnings to confirm that there
-    // isn't any other warning before clicking the link.
-    // @todo Make this more reliable in
-    //   https://www.drupal.org/project/drupal/issues/2927345.
-    $selectors = [];
-    for ($i = 0; $i <= count($expected_warnings); $i++) {
-      $selectors[] = 'h3#warning' . implode('', array_fill(0, $i + 1, '+details')) . ' summary';
-    }
-    $warning_elements = $this->cssSelect(implode(', ', $selectors));
-
-    // Confirm that there are only the expected warnings.
-    $warnings = [];
-    foreach ($warning_elements as $warning) {
-      $warnings[] = trim($warning->getText());
-    }
-    $this->assertEquals($expected_warnings, $warnings);
+    $this->assertFalse(strpos($this->getTextContent(), 'Errors found'));
+    $this->assertWarningSummaries($expected_warnings);
     $this->clickLink('continue anyway');
     $this->checkForMetaRefresh();
   }